var btns=document.getElementsByClassName("gbzt");
for(var i in btns){console.log(btns[i]);
if (btns[i].href)
	btns[i].href=btns[i].href.replace("www.google.com","g.yooooo.us");
}
var logo=document.getElementById("logo");
logo.href=logo.href.replace("www.google.com","g.yooooo.us");